distributed-database-middleware/umn/source/sql_syntax/dml/select_union_syntax.rst

original_name

ddm-08-0011.html

SELECT UNION Syntax

Common Syntax

SELECT ...UNION [ALL | DISTINCT]
SELECT ...[UNION [ALL | DISTINCT] SELECT ...]

Example

select userid from user union select orderid from ordertbl order by userid;
select userid from user union (select orderid from ordertbl group by orderid) order by userid;

Syntax Restrictions

SELECT statements in UNION do not support duplicate column names.